Where to get an OEM fan clutch?

[joe_peters]

Mine was a 272310, not sure how I skipped a number ha.

The picture above is not my picture, but it shows the height difference that I had. My old clutch I can't confirm to be original but it sure looks like it was. It has no part numbers on it so it very well maybe an aftermarket one.

Everything still fit fine(aside from having to tilt the radiator to make room to clear the mounting studs. There is plenty of clearance between the fan clutch and my 3 core radiator.

Good to know on the clearance with the 3-core, I may be adding one of those in the future. Appreciate the feedback.

 

[winkosmosis]

haha yeah the ZJ clutch sounds like a jet. Mine got a tad bit annoying though after awhile.

I thought it was supposed to spin the usual slow speed when not hot

 

[joe_peters]

I thought it was supposed to spin the usual slow speed when not hot

It does, he's talking about when engaged. Standard and HD both at 30 percent of shaft speed disengaged. Standard is 60-70 percent, HD is 80-90 percent when engaged.

 

[carves]

Anybody got any info on this fanclutch ???

Rugged Ridge/OmixAda ..... part # 17105.03

Comes wrapped in a box with USMW branding ... and labelled "heavy duty"

 

[winkosmosis]

It does, he's talking about when engaged. Standard and HD both at 30 percent of shaft speed disengaged. Standard is 60-70 percent, HD is 80-90 percent when engaged.

But I would think that at a normal temp it wouldn't be spinning much faster

 

[Jeepguy03]

It does, he's talking about when engaged. Standard and HD both at 30 percent of shaft speed disengaged. Standard is 60-70 percent, HD is 80-90 percent when engaged.

really? Mine seemed like it was always engaged. I even went to 3500 RPMs and it was still locked. Even in the fall when the jeep was running around 180* with the ZJ clutch. Is mine faulty? We put one in my friend's '89 XJ which didn't have any overheating issues and it did the same thing. :scared:

 

[joe_peters]

Engine RPMs don't mean anything. The thermal fan clutch comes on when the air coming through the radiator and hitting the bi-metal spring on the front of the fan clutch hits 170 degrees, then the bi-metal spring starts to open the valve that allows the silicone fluid to leave the reservoir and begin to engage the clutch. It is completely independent of engine RPMs, that is why the fan clutch will engage when idling or at highway speeds.

When the engine is shut off, like overnight, the silicone fluid will leak past the valve. That is why ALL thermal fan clutches will engage when cold, until the fluid is spun back into the reservoir.

So, either you had bad fan clutches, or way too efficient heat transfer from the radiator to the air flowing through it.

 

[winkosmosis]

I think what he means is that at higher rpm the air resistance should overcome the torque and it would spin slower than rpm... Although you wouldn't be able to tell, it would still spin faster at higher rpm.

 

[joe_peters]

Well, if it turns at 30 percent of shaft speed disengaged, it would be spinning as a percent of any engine RPM, same thing with engaged.

 

[Jeepguy03]

Well, if it turns at 30 percent of shaft speed disengaged, it would be spinning as a percent of any engine RPM, same thing with engaged.

So your saying that the ZJ clutch should act exactly like a factory fan clutch except when its engaged it will lock up 80-90% vs. the 60-70% of the stock one? If thats the case then my ZJ clutch was bad right out of the box. I currently have a mopar factory clutch in there right now, below 60* I never hear it and my temps are 190*. As soon as it gets above 70* and the temps are closer to 210* I can hear it roar when accelerating from a stop light. The ZJ clutch was locked up all the time. It sounded exactly the same (fully engaged) if the engine was normal temp, or if it was cold. Even during the fall it still was fully engaged even when temps were in the 40s and 50s. My jeep was running about 170* so I had to take it out. I was told by my mechanics shop teacher that fan clutchs will disengage when they reach a certain RPM. I've seen posts about the ZJ clutch disengaging around 3000 RPM, so I tried it to see what happened. Under full throttle it still was fully engaged. Sounded like a jet and actually scared my friend haha.

I guess mine was bad but I always thought they stayed locked like that because the XJ fan is smaller than the ZJ fan with blades of a different pitch so thats less resistance for the clutch.

 

[iwannadie]

How are you guys able to visually see the fan spinning at 60-70% Vs. 80-90%? I have some dam good eyes and it just looks like a blur to me lol. No way I could differentiate a 10% difference in fan speed at those RPM. Maybe If I saw them side by side I could pick out the slower one but looking at it and thinking "Yea, that looks 10% slow to me.".

Or am I missing something when talking about the fan engaging?

 

[winkosmosis]

I think people go by the sound

 

[joe_peters]

How are you guys able to visually see the fan spinning at 60-70% Vs. 80-90%? I have some dam good eyes and it just looks like a blur to me lol. No way I could differentiate a 10% difference in fan speed at those RPM. Maybe If I saw them side by side I could pick out the slower one but looking at it and thinking "Yea, that looks 10% slow to me.".

Or am I missing something when talking about the fan engaging?

Its how the standard vs. HD fan clutches are designed. However, you could rig up an optically triggered tach system to measure the RPMs of the fan, do the math for the shaft speed of the fan pully at a given engine RPM to get your readings, or listen for difference in the amount of air getting pulled, or watch your temp gauge.

 

[joe_peters]

I think people go by the sound

You get a cookie!

 

[joe_peters]

So your saying that the ZJ clutch should act exactly like a factory fan clutch except when its engaged it will lock up 80-90% vs. the 60-70% of the stock one?

Yes.

I've seen posts about the ZJ clutch disengaging around 3000 RPM

No. The only fan clutches with any RPM related function are the NON-THERMAL fan clutches, and the RPM limits on those are application specific.

 

[iwannadie]

Its how the standard vs. HD fan clutches are designed. However, you could rig up an optically triggered tach system to measure the RPMs of the fan, do the math for the shaft speed of the fan pully at a given engine RPM to get your readings, or listen for difference in the amount of air getting pulled, or watch your temp gauge.

Ok, I thought you guys were just looking at the fan and able to tell the rotational speed accurately.

 

[joe_peters]

From the 90 FSM:

"The cooling system must be in good condition prior to performing the test outlined below to ensure against excessively high coolant temperature.

CAUTION: Ensure that there is adequate fan blade clearance before drilling.
(1) Drill a 3.18 mm (1/8 in) diameter hole in the top center of the fan shroud.
(2) Insert a dial thermometer -18 degree to 105 degree C (0 degree to 220 degree F) with an 8 inch stem, or equivalent, through the hole in the shroud. Ensure that there is adequate clearance from the fan blades.
(3) Connect a tachometer and an engine ignition timing light (to be used as a strobe light).
(4) Block the air flow through the radiator by securing a sheet of plastic in front of the radiator (or air conditioning condenser). Use tape a the top to secure the plastic and ensure that the air flow is blocked.
(5) Ensure that the air conditioner, if equipped, is turned off.
WARNING: USE EXTREME CAUTION WHEN THE ENGINE IS OPERATING. DO NOT STAND IN DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE PULLEYS, BELTS, OR FAN. DO NOT WEAR LOOSE CLOTHING.
(6) Start the engine and operate at 2400 rpm with the timing light (strobe light) aimed at the fan blades. Within ten minutes the air temperature (indicated on the dial thermometer) should be 88 degrees C (190 degrees F). Satisfactory operation of the fan drive requires that it engage before or at 88 degree C (190 degree F). Engagement is distinguishable by a definite increase in the flow noise. The timing light will also indicate an increase in the speed of the fan.
(7) When the air temperature reaches 88 degrees C (190 degrees F) remove the plastic sheet. Satisfactory operation of the viscous fan requires the air temperature to drop 20 degrees F (11 degrees C) or more. A definite decrease of audible fan air flow noise should be noticed. Replace defective fan assemblies."

 

[robhurlburt]

how do i know if my OEM fan clutch is good or not?

 

[casm]

how do i know if my OEM fan clutch is good or not?

Take a look at this thread; it has both the basic test and replacement procedures.

FWIW, it's worth upgrading it to the ZJ HD fan clutch while you're in there (assuming you have a 4.0). NAPA p/n 272310; use that specific one. Price is about $5 more than the standard XJ unit.

 

[yardape]

I had a POS aftermarket radiator in my XJ for awhile installed by a body shop. It overheated all the time. I replaced the fan clutch cuz I never heard it come on. Then I replaced the radiator with a csf 3 row and guess what,... now I hear the fan clutch all the time. Its the standard NAPA part. Just food for thought but when its working you definitely can hear it going on and off.